Field of Invention
This invention relates to buffer amplifiers and more particularly to an amplifier which is capable of changing output current level rapidly without need for high levels of quiescent current.
Conventional DC-coupled linear amplifiers commonly use push-pull output stages that alternate between on and off conduction conditions on applied signals of alternating polarity. Thus, during positive rise of output current, one output stage is heavily conductive and another output stage is tending toward non-conduction. The conditions reverse on negative rise of output current. For high rates of change, the current through the heavily conductive output stage may not be sufficient to keep up with the load requirement and output signal distortion results. One technique used to overcome this condition included increasing the quiescent current level in the output stages to assure that ample current is available during rapid changes. However, this technique has the disadvantage of requiring substantial levels of idle current from the power supply with concomitant higher power dissipation, and higher junction temperatures which may require heat sinks.